(a) Technical Field
The present disclosure relates to a thin film transistor array panel for a liquid crystal display and a manufacturing method thereof.
(b) Discussion of the Related Art
A liquid crystal display (LCD) includes a pair of display panels having field generating electrodes and polarizers, and a liquid crystal layer interposed between the two display panels. A field generating electrode generates an electric field on the liquid crystal layer. The arrangement of liquid crystal molecules in the liquid crystal layer varies as the intensity of the electric field changes, thereby changing the polarization of light passing through the liquid crystal layer. A polarizer blocks or transmits the polarized light appropriately to make bright and dark regions, thereby displaying desired images.
One of the display panels includes a plurality of pixels having switching elements and a plurality of display signal lines, and a gate driver having a plurality of stages transmitting gate signals to gate lines of the display signal lines to turn on/off the switching elements of the pixels.
Each stage of the gate driver is connected to one of the signal lines, and the stage receives a gate on/off voltage and a clock signal, and transmits the inputted gate on/off voltage and clock signal to the signal line connected thereto.
The gate driver may be integrated with the substrate, and then the gate lines may extend to connect to the gate driver directly. Here, for connecting gate wires of the gate driver and data wires of the gate driver, contact holes exposing the gate wires are formed. The data wires are connected to the gate wires through the contact holes using a connecting member which may be made of Indium Tin Oxide (ITO).
Alternately, if the gate driver is formed outside of the substrate, pad portions, which connect the gate on/off signal lines to the stages of the gate driver, are required for transmitting the gate on/off voltage to the stages of the gate driver. Here, for connecting the pad portions to the signal lines, contact holes exposing the signal lines are formed, and then the signal lines are contacted to the stages of the gate driver through the contact holes using a connecting member which may be made of ITO.
As the lengths of the signal lines increase along with the LCD size, the resistance of the lines increase, causing a signal delay or a voltage drop. In response to the increased resistance, wiring is made from of a material having a low resistivity, such as aluminum (Al). When Al is used in wiring, signal lines may have a multi-layered structure including an Al layer and another layer. However, if the signal lines including Al contact with the ITO used in pixel electrodes or connecting members of an LCD directly, then the Al may become oxidized or corroded.
The thin film transistor array panel of a liquid crystal display includes a plurality of thin layers such as a gate layer, a data layer, and a semiconductor layer. The thin layers are respectively patterned by photolithography processes using separate photo-masks. However, when adding one additional mask, various steps such as exposing, developing, and cleansing are repeated, and thereby manufacturing time and cost significantly increase.
Accordingly, there is a need for a thin film transistor array panel with improved resistance to oxidation or corrosion and a method of manufacturing the same which can reduce the time and expense of manufacturing.